1. Field of the Invention
The structure and method of this invention reside in the area of airship/balloon envelopes such as used in blimps, dirigibles and other types of lighter-than-air structures which lift objects, and more particularly relate to a system of maintaining hydrogen gas within the cells of a foam in such airship/balloon envelopes.
2. Description of the Prior Art
Airships such as blimps and dirigibles have long been in use and hydrogen gas has been utilized to cause the craft to be lighter than air. Problems, though, arose with the use of hydrogen gas since it is highly inflammable. To replace hydrogen, helium has been used, but helium is expensive while hydrogen can be made inexpensively by the simple electrolysis of water. Fire retardant foams using polyglycols have been used in the past to smother fires.